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Item In Situ Radiolysis Electron Spin Resonance Study of the Radical-anions of Substituted Nitroimidazoles and Nitroaromatic Compounds(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1978, 74 (3), 1978) Ayscough, Peter B.; Elliot, A. John; Salmon, G. ArthurReaction of e–aq, (CH3)2ĊOH, (CH3)2CO[graphic omitted] or CO[graphic omitted]2 with a number of substituted nitroimidazoles and nitrobenzenes results in the formation of their radical-anions and in no case were radical-adducts detected. Changes in the e.s.r. spectra of the product species with pH are interpreted in terms of either the protonation of the radical-anion (metronidazole) or the loss of a proton from the radical anion (2-methyl-5-nitroimidazole, 4-nitroimidazole and nitrophenols) and pK values of some of these processes are evaluated. In several cases the dynamics of these acid–base reactions influence the linewidths of the e.s.r. spectra.Item Solute Ion and Radical Formation in the Pulse Radiolysis of Acetonitrile Solutions(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1974, 70 (11), 1974) Baptista, Joao L.; Burrows, Hugh D.Following microsecond pulse radiolysis of solutions of a variety of solutes in acetonitrile, absorptions assigned to solute cation radicals, anion radicals, excited states and neutral radicals are observed. Pulse radiolysis of solutions of tri-p-tolylamine or triphenylamine yields the amine radical cations, whose absorptions are observed to grow-in by a second-order process after the electron pulse. We report rate constants for this process, which is suggested to be electron transfer to acetonitrile radical cation or cation dimer. Yields of G∼0.2 are reported for the oxidizing species. Oxidation via a different route involving hydrogen atom transfer is suggested to occur following pulse radiolysis of solutions of phenol or phenothiazine. Pulse radiolysis of solutions of benzophenone or biphenyl yields the solute radical anions in agreement with previous studies on this system. The mechanism of acetonitrile radiolysis is discussed with a consideration of this and previous studies.Item Free Radical Yields in the Radiolysis of Gaseous Hexafluoroethane(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (5), 1973) Cooper, Ronald; Robert Haysom, HowardThe radiolysis of gaseous hexafluoroethane yields CF4(G= 2.5), C3F8(G= 0.31) and C4F10(G= 0.10) as major products. In the presence of Br2, Cl2 or HCl these products are scavenged and replaced by yields of CF3 and C2F5 scavenged products. The yields of these scavenged products are independent of pressure above 5 mol % scavenger and are ∼G= 2.6 for both CF3 and C2F5 radicals. In the presence of chlorine and HCl, not all the CF4 is scavengeable even though the CF3 and C2F5 radical yields are independent of scavenger concentration. Statistical combination–cross combination ratios may be used to reconcile the observed radical yields with the yields of stable fluorocarbon products. Competition kinetics in the Br2+ Cl2+ BrCl system indicate that some of the CF3 scavenged products are due to either hot radicals or ions.Item Radiolysis of Benzene+Bromobenzene Solutions(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (3), 1973) Kumar, S. S.; Merklin, J. F.Yields of γ-ray radiolysis products from benzene, bromobenzene and solutions of benzene and bromobenzene have been measured. The yield of biphenyl was larger in the solutions than in either of the pure solvents. Rate constants for quenching reactions were estimated on the basis of the measured product spectra and the published value of the ratio of rate constants for quenching in benzene +p-terphenyl + bromobenzene solutions.Item Radiolysis of Carboxylic Compounds: Part 1.—Comparison of Potassium Acetate and Acetic Acid Radiolysis(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (8), 1972) Lukac, S; Teply, J; Vacek, KMeasurement of the yields of CO2, CO, H2, CH4, C2H6 and of trapped paramagnetic species reveals substantial differences in the radiolysis of CH3COOH and CH3COOK both at room temperature and 77 K. Microwave power saturation of e.s.r. spectra in both CH3COOH and CH3COOK was observed. Anion radical (CH3COOH)– is the main trapped paramagnetic species in CH3COOH at 77 K; an additional structure at microwave power below 15 µW was discovered. In irradiated CH3COOK the radical · CH2COO– was found as a main paramagnetic species; in addition to that a quartet assigned to · CH3 radical and a broad singlet were observed. The temperature dependence of the final product yields and of paramagnetic species is also presented. The possible reasons for the differences observed in the radiolysis of both compounds are discussed.Item Nanosecond Pulse Radiolysis of Acetone: Kinetic and Thermodynamic Properties of Some Aromatic Radical Cations(Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1972, 68 (7), 1972) Rodgers, M. A. JSpectra of the molecular ions of acetone, formed during liquid phase pulse radiolysis arc reported. The kinetic features of the monomer-dimer cation equilibria of some aromatic hydrocarbon solutes have been obtained at a number of temperatures. Equilibrium constants and thermodynamic data are measured and their implications discussed. The data are compared with literature values for the analogous equilibria involving excited singlet monomers and excimers.